I hope there is a simple answer to this. Do I need to install the RCA pre-out harness? The only wire on there that I will be using is the "Mute" wire for the hardware bypass.

If I do the software bypass will I really need this harness?

Either way you dont need it. You can solder the mute wire to the appropriate pin on the unit, and still do the hardware bypass...or you can do the software bypass and do away with it completely (software bypass only requires the parking break wire to be grounded)

yeah if you want your ipod to work since you already have the cable